Doppler shift measurements

The X- and Ka-band Doppler shifts measured from wind-generated waves on a water surface covered with oleyl alcohol (OLA) are shown in Figure 8. It is obvious that the coverage of the water surface with a sur-... 

Coming back to our comparison we find that beyond mass A 40 (with all other parameters unchanged) the time-of-flight resolution will become superior to the optical resolution. But the energy dependence shows that for beam energies above a few keV the Doppler shift measurement becomes definitely more favorable. Moreover, the choice of a weak transition... 

There are two types of size characterization equipment based on laser Doppler shift measurement. In the first technique, the fineparticles under study move through a region illuminated by a laser beam. The Doppler shifts generated by the moving fineparticles are evaluated and related to the velocity of the fineparticles under study. The method used to study fineparticles less than 1 micron in size utilizes the Doppler shift created by Brownian motion as monitored with a laser beam [1]. This second type of technology is variously known as photoncorrelation spectroscopy (PCS) or dynamic light scattering (DLS). 

The scattering techniques, dynamic light scattering or photon correlation spectroscopy involve measurement of the fluctuations in light intensity due to density fluctuations in the sample, in this case from the capillary wave motion. The light scattered from thermal capillary waves contains two observables. The Doppler-shifted peak propagates at a rate such that its frequency follows Eq. IV-28 and... 

A method which competes with interferometric distance measurement is laser Doppler displacement. In this approach the Doppler shift of the beam reflected from a target is measured and integrated to obtain displacement. This method also is best suited to use indoors at distances no more than a few hundred meters. Table 2 compares some of the characteristics of these laser-based methods of distance measurement. 

Ultrasonic methods can also be applied to velocity measurements based on measurement of the Doppler shift in the frequency of an ultrasonic wave scattered from a moving particle. The angle between the velocity vector and the direction of ultrasound propagation must be known, which practically limits the appHcation of the technique to the measurement of unidirectional flows. However, this Hmitation may be overcome again by the use of an array of transducers [11]. 

Dunning, JW Angus, JC, Particle-Size Measurement by Doppler-Shifted Laser Light, a Test of the Stokes-Einstein Relation, Journal of Applied Physics 39, 2479, 1968. 

Cahbration spectra must be measured at defined temperamres (ambient temperature for a-iron) because of the influence of second-order Doppler shift (see Sect. 4.2.1) for the standard absorber. After folding, the experimental spectrum should be simulated with Lorentzian lines to obtain the exact line positions in units of channel numbers which for calibration can be related to the hteramre values of the hyperfine splitting. As shown in Fig. 3.4, the velocity increment per channel, Ostep, is then obtained from the equation Ustep = D,(mm s )/D,(channel numbers). Different... 

In this section, the relationship between the measured quantity and the desired center-of-mass differential cross-section will be established and a brief description of the data analysis procedure will then be given. First, consider a Newton sphere with a single value of the product velocity v (see Fig. 4). From the Doppler-shift formula, at a given laser wavelength, the Doppler effect selectively ionizes those ions with vz = vcosO in the... 

To sum up, the basic idea of the Doppler-selected TOF technique is to cast the differential cross-section S ajdv3 in a Cartesian coordinate, and to combine three dispersion techniques with each independently applied along one of the three Cartesian axes. As both the Doppler-shift (vz) and ion velocity (vy) measurements are essentially in the center-of-mass frame, and the (i j-componcnl, associated with the center-of-mass velocity vector can be made small and be largely compensated for by a slight shift in the location of the slit, the measured quantity in the Doppler-selected TOF approach represents directly the center-of-mass differential cross-section in terms of per velocity volume element in a Cartesian coordinate, d3a/dvxdvydvz. As such, the transformation of the raw data to the desired doubly differential cross-section becomes exceedingly simple and direct, Eq. (11). 

The Doppler-selected TOF technique is one of the laser-based techniques for measuring state-specific DCSs.30 It combines two popular methods, the optical Doppler-shift and the ion TOF, in an orthogonal manner such that in conjunction with the slit restriction to the third dimension, the desired center-of-mass three-dimensional velocity distribution of the reaction product is directly mapped out. Using a commercial pulsed dye laser, a resolution of T% has been achieved. As demonstrated in this review, such a resolution is often sufficient to reveal state-resolved DCSs. 

The Doppler shift correction is somewhat of a circular argument in that the best way to determine the Doppler shift is to measure the shift of a known spectral line... 

To understand this effect more quantitatively, consider an idealized measurement of Doppler shifts from one member of a binary, call it star 1. Assume that both objects are effectively point masses. One can measure the period P of the orbit and the velocity semiamplitude Vi of star 1 in the direction of the line of sight. If the two stars have masses mi and m2 and are orbiting in a circle with a semimajor axis a and an inclination i (such that i = 90° means an orbit edge-on to our line of sight), then... 

So by measuring the second-order Doppler shift of the Mossbauer nuclei in a material it is possible to determine their average velocity and thus their average vibrational kinetic energy, /2, where the mass of the Mossbauer nucleus. The... 

Doppler-free two-photon spectroscopy spect A version of Doppler free spectroscopy in which the wavelength of a transition Induced by the simultaneous absorption of two photons is measured by placing a sample In the path of a laser beam reflected on itself, so that the Doppler shifts of the Incident and reflected beams cancel. dap-lor fre tu fO,tan spek tras-ka-pe j... 

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